In the spectral composition of sunlight, far-infrared radiation is low energy radiation that is capable of penetrating into the hypodermic layer of human skin. The vibration frequency of the far-infrared radiation is similar to that of human cells. As a result, the far-infrared radiation is capable of increasing cellular metabolism and blood circulation, and therefore is beneficial to eliminating waste from the body. Currently, mineral particles capable of emitting far-infrared, such as aluminum oxide, zirconium dioxide, titanium dioxide, yttrium oxide, and combinations thereof, are incorporated into application materials. By using special processing techniques, the application materials are increased in value and made into various items used in daily life.
Referring to FIG. 1, a conventional floor board 10 includes two board units 1, each of which includes a substrate 11 and a wear resistant layer 12. The substrate 11 of each of the board units 1 has a first side surface 112, a second side surface 113 opposite to the first side surface 112, a top surface 111 interconnecting the first and second side surfaces 112, 113, a male engaging part 114 extending outwardly from the first side surface 112, and a female engaging part 115 indented inwardly from the second side surface 113. The male engaging part 114 corresponds in shape to the female engaging part 115. The male engaging part 114 of the substrate 11 of one of the board units 1 engages with the female engaging part 115 of the substrate 11 of the other one of the board units 1. The wear resistant layer 12 of each of the board units 1 is disposed on the top surface 111 of the substrate 11 of the board unit 1, and has a plurality of micro grooves 121 to form a plurality of wood grain patterns 122.
When a paste (not shown) including a far-infrared material is applied onto the wear resistant layer 12 of each of the board units 1, the paste may fill the micro grooves 121 of the wear resistant layer 12 and damage the wood grain patterns 122.
Referring to FIG. 2, the friction between the male engaging part 114 and the corresponding female engaging part 115 may cause the engagement process to be unsmooth, and may even fracture the corresponding board unit 1 to form a plurality of cracks 2.